SPS particle accelerator at CERN

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Caption: The tunnel of the Super-Proton-Synchrotron (SPS) particle accelerator at CERN, the European particle physics laboratory outside Geneva. The SPS first accelerated protons in 1976, achieving energies of 400 GeV. Since 1981, the machine has also operated as a proton-antiproton collider, with the same bending magnets (red) guiding protons and antiprotons around the ring in opposite directions. The accelerator forms an underground ring 7 km in circumference.